After four years of joint operation of the Nordic Food Lab (NFL), the NFL’s Board of Directors will transfer the entire NFL to the Department of Food Science at the University of Copenhagen (UCPH FOOD). The self-governing NFL will close down, while its activities will continue as part of the Future Consumer Lab

Chairman of the NFL Board Claus Meyer and Head of UCPH-FOOD Anna Haldrup, pictures by Thomas Grøndahl and Claues Boesen.

For four years, UCPH FOOD and the NFL’s Board of Directors have jointly operated the Nordic Food Lab, whose task has been to explore tastes and foods from the Nordic region. NFL was started by Claus Meyer and René Redzepi in 2008 and it became a part of UCPH FOOD in 2014 to bring together gastronomy and food science in the exploration of taste in relation to, among other things, resource utilisation and sustainability. The collaboration has led to many exciting results and, while the self-governing institution is closing down, the NFL’s research into taste and sustainability will continue in the Future Consumer Lab at UCPH FOOD.

The creation of NFL in 2008 was the result of an idea to raise the level of ambition for product development in the food industry by involving chefs in the conversation between the university’s basic research, agriculture and the food industry. The aim was sustainable and more palatable food products with stronger entrepreneurship and greater innovation.

“From the perspective of the board of directors, this mission has been accomplished. Therefore, we are now transferring the activities of the Nordic Food Lab to the Department of Food Science at the University of Copenhagen, which will continue the tradition of close collaboration with the world of gastronomy. Over the years, Nordic Food Lab’s employees, interns and students have created an impressive amount of knowledge and their activities have attracted international attention and inspired similar environments elsewhere. The good news then is that the University of Copenhagen is not alone in managing the legacy,” says Claus Meyer, the Chairman of the NFL Board.

“We would like to give a heartfelt thanks to Claus Meyer and the rest of the Board of Directors for the work they have done over the years. The NFL has especially contributed to the exploration of new raw materials in regional contexts with respect for resources and societal cultures in a way that has helped set the bar higher for both gastronomy and food science,” says the head of FOOD at the University of Copenhagen, Anna Haldrup. She continues:

“At UCPH FOOD we aim for an even broader approach to gastronomy, with even deeper roots in our food educational programmes and research. By collaborating at all levels with both Nordic and international partners, we are uniquely placed to come up with solutions that contribute to positive social development when it comes to food production, gastronomy, flavour, sustainability and public health. We are also very pleased that the NFL is assigning its assets to us, which will benefit both researchers and students at the University of Copenhagen.”

The Future Consumer Lab at UCPH FOOD works with food science from a consumer perspective. The research contributes to sustainable development, including improved public health, by linking consumer food preferences to the development of new foods. Gastronomy, taste analysis, sensory science, consumer analyses and the dissemination of knowledge about food and consumers are important elements of the laboratory’s work.

Written by Julia Sick, edited by Michael Bom Frøst, photos by Yi-Ting Sun.

And we did it again! The Nordic Food Lab hosted its 4th Monday Aperitivo at the University of Copenhagen on the 19th of March. Our guest speakers included Rasmus Kristensen from Jalm&B, Associate Professor Emerita Åse Hansen from the Department of Food Science at University of Copenhagen and bartender Hardeep Rehal owning the cocktail bar Blume in Copenhagen.

The ingredients for this time’s lecture were flour and water…and some microorganisms, which are most often overseen too easily despite their importance to bring that gluey mass of dough to life.

Human’s use of the living culture can be tracked back 5000 years. Back then, people did not have an explanation for the spontaneous rise of bread, and rather explained it by either magic or religion. With the development of scientific microbiology in the 19th century, the rise of bread was attributed to the presence of wild yeasts from the atmosphere. They form a symbiotic relationship with lactic acid bacteria that create the characteristic sourness in the dough that is not present in most bread made with baker’s yeast.

The science table

All guests started with a tour around the “science table”. You cannot see the tiny microbes with the naked eye; however, you can see and smell the consequences of their microbial activity.

A set-up of various samples demonstrated influences of different grain varieties, fermentation time and temperature. A little “pre-taste”, if you can say so…

Set-up of the science table with different sourdough starter cultures and grain varieties.

Microscopic image of wild yeast and lactic acid bacteria from a cultivated rye sourdough. The LAB:yeast ratio in sourdoughs is generally 100:1.

The debate of the flavor creator

While the smell of freshly baked bread already crossed our smell receptors, we moved straight to our research kitchen to listen to the interactive talks between Åse and Rasmus.

But before that Rasmus, who clearly masters his craftsmanship, prepared some tasters of freshly baked sourdough bread and asked for a short sensory evaluation. We concluded on a mouth-watering bread with complex flavor and a balanced acidity, good crust and a moist crumb that was “gelatinized” with evenly distributed alveoli (wholes in the bread).

Åse, the omniscient researcher with over 50 years of experience in sourdough enriched our knowledge about its microbiology and fermentation properties. As she informed us, the sourdough flavors are developed during a long fermentation process that requires at least 12-24 hours, while fermentation through baker’s yeast only takes 1-2 hours. The lactic acid bacteria are mainly responsible for the acidification of the sourdough, whereas the yeasts are very important for the production of flavor compounds and some acids.

Rasmus mentioned that the bread that we purchase nowadays in supermarkets are most often made with commercial yeast, undergo a very short fermentation and contain various additives for preservation and taste. Therefore, he supports the idea to provide supermarkets with sourdough bread to make it available for all of us, however, this brings its challenges. One of the main difficulties is to maintain a stable culture of wild microorganisms to control the fermentation process and to achieve the same results each time. Sourdough needs to be more controlled as the variation in the composition of specific microorganisms depends on the fermentation conditions, such as flour type, extraction rate, water content, fermentation temperature, fermentation time, and how the sourdough is refreshed, as Åse explained.

Rasmus shared his experience that when serving his own bread to his friends and colleagues, they observed easier digestibility and overall better well-being. Åse explained this by the fact that grains cannot be fully digested by human, but a long fermentation allows the present microorganisms to “predigest” the indigestible compounds for us. Additionally, the nutritional value is enhanced by the use of whole grain flour as it contains a higher content of free minerals, which are made available for us during the long time of fermentation as phytate, a phytic acids, prevents the absorption of these minerals.

What’s sourdough doing in a cocktail?

For our aperitifs, we had the honor to host Hardeep. For a second, you might wonder what cocktails have to do with sourdough? And well, after this afternoon we can tell you: a lot. The first drink created was based on a sourdough extraction, basically, a rye sourdough fermented for 48h, centrifuged and pasteurized. The extraction added a mix of fruity, tangy and lemon-like flavors that he combined with Aquavit, unripe rhubarb juice and fresh dill.

Grains are the fundament for making sourdough, so the second drink was based on an extraction of 2h slowly roasted and milled purple wheat. The liquid was siphoned with nitrous oxide directly into a glass, which resulted in an exceedingly creamy and delicate texture with savory notes of cacao, coffee and cardamom.

Participate in GASTRO-SCIENCE-CHEF 2018 - an international two-day symposium on science and cooking hosted by The Department of Food Science (FOOD) at the University of Copenhagen.

In the last couple of decades we have witnessed an increasing interaction between chefs and scientists, fueling new trends in both cooking and research. This two-day symposium brings together chefs, scientists, students, and culinary entrepreneurs to discuss matters of mutual interest with the aim of further cross-fertilization and developing of new ideas for future and collaborative work. A particular emphasis will be on communication and public outreach.

The symposium will include workshops with gastronomic and gastrophysical demonstrations and experimentation.

The 4th Wild & Feral Food Week 2018 is founded by our friends at Berkeley Open Source Food. The purpose is to connect produce suppliers, markets, and restaurants to create a space for wild and feral edible plants to provide interesting, delicious ingredients for consumers and chefs.

Nordic Food Lab hosts and contributes to the event Wild Aperitivo to showcase the delicious potential of wild and feral foods in our own community. The Wild Aperitivo to some degreee follow our Monday Aperitivo. It is an informal forum, where people can address their views with an amount of passion of a specific subject related to food. A forum from where dialogues and discussions between sciences, craftsmanship and industry take place to stimulate the appetite for progress.

The program for the event We will offer lectures, showcases, discussions, and small tastings on wild foods presented by our special guest Professor from UC Berkeley and founder of BOSF, Philip B. Stark, Chef Søren Ejlersen from Årstiderne and Lene Ejlersen, the authors of the recent book Vildnis (lit. Wilderness) as well as Head of culinary research and development at Nordic Food Lab, Roberto Flore, and the two Mixologists Mads Schack and Hardeep Rehal.

Join us on informative lectures and be part of our interactive showcases that highlight the use of wild food in gastronomy. Tickets are for sale at billetto. Remember to sign up for the showcases prior to the event. More details about these will follow via email. Stay tuned!

We were very excited to host our 3rd Monday Aperitivo 29th of January after our previous successful Monday Aperitivo in 2017. A concept where science and culinary techniques meet for a kitchen talk to stimulate appetite! This time, squids from the North took the stage of discussion, reflection and our palates.

A new year is approaching. Throughout December the Lab has been smelling of pine (α-pinene), cinnamon (cinnamaldehyde), cloves (eugenol), oranges (octyl acetate) and gløgg - the Danish mulled wine. It is a time to enjoy meals together with family and friends and to remember all the pleasant memories from the past year, and to make a brief inventory of the activities in the lab. Therefore, we would like to share some of our best memories from 2017 with you.

November 27, we held our second Monday Aperitivo. This time the theme was the kingdom of fungi, in a broad definition. The idea of this Monday Aperitivo was to discuss and engage in the diversity of fungi and their potential for creating deliciousness in foods.

Welcome our new initiative, which has been in the making for a long time; Monday Aperitivo.Take an ordinary Monday, the last Monday of the month. Spice it up with concepts such as “Gastrophysics”, “Interdisciplinarity” and well, “aperitifs” and your Monday is not so ordinary anymore.

Our friends and collaborators at Smag for Livet are behind this exciting symposium at Aarhus Theater September 4-5. Nordic Food Lab contribute to the organisation of the content and will give a few tasters as part of the conference.

This unusual symposium offers a unique possibility for gastronomic reflection on the concept of taste. The symposium will present viewpoints from leading individuals from both the arts and the sciences, and performers from the creative sector will explore and challenge these viewpoints by engaging in a in dialogue with scholars as well as orchestrating experiments with the audience.

A NUMBER OF INNOVATIVE SHOWCASES AND SOAP BOX DIALOGUES With contributions from the audience

It will inspire a broad audience – from researchers to restaurateurs, architects, food producers, chefs, and food writers. With its cross-disciplinary and creative approach the event invites for new and creative collaborations, thereby making it possible to ask new questions on the meaning of taste: How can we think architecture and taste together? What is the relation between taste and nutrition? How do we share our experiences of taste? How can we talk about taste in a new language? Through engaging in these themes, and many others, the symposium contributes to the ongoing work of developing gastronomy in the region.The symposium is a platform for rethinking: from concepts for restaurants, ideas for research, ways of building kitchens to ideas for menus, food products and cook books.

Spice mixes are cornerstones of kitchens all over the world. The distinct flavours that is most often used in a cuisine are basic principles that determine that cuisine, so-called flavours principles (E Rozin & Rozin, 1981; Elizabeth Rozin, 1983). Some years ago we set out to characterise a good pool of 29 spice mixes of various origins –some classical ones from different parts of the world, some experimental ones that we ourselves at the lab had created and one that was donated to us from noma. The outcome of the sensory descriptions from 26 kind food professionals that donated their time and delicate palates to us is described previously in Calibrating Flavour part I. There are many pros and some cons of the sensory methods that we used (Frøst, Giacalone, & Rasmussen, 2015). It is very fast to duo, and can be carried out in almost any location that is relatively quiet and without too much sensory distraction such as smells and fragrances. On the other hand, the results will not be as precise as a traditional descriptive analysis carried out by a trained sensory panel. But for our purpose, to get an overview of the interrelations between a large group of spice mixes, it was precise enough. The results are extremely useful, and were created with a very small financial burden to us.

But there was much more to this audacious adventure. At University of Copenhagen’s Department of Food Science, the spice mixes were analysed by Headspace Gas Chromatography under conditions that simulate the conditions during eating a food, where the aromatic volatiles of the food enter the nose via the back of the throat (the retronasal pathway, (Shepherd, 2006)). Further, the aroma molecules were identified by mass spectroscopy (so-called GC-MS, Hübschmann, 2015).

The purpose of this was to study and visualise information of very different origins, but all characterising the same 29 spice mixes. There are 4 types of information that we can link:

Sensory descriptors (Words) - In addition to the positions from the projective mapping, there are also a number of words that the sensory respondents (the food professionals) have attached to the spice mixes. After some textual analysis of the original set of words (totalling 545 different words), this set of data consists of a matrix with 29 rows and 113 columns – 113 different and relevant words that escribe the sensations of the spice mixes.

Aroma profiling (Odour chemicals) - Through headspace sampling, GC-MS analysis was used to obtain an aroma profile for each spice mix. The aroma profile consisted of the relative integrated peak area (relative concentration) of 122 different odorous compounds. Some of the compounds have available sensory descriptors, collected in a smaller matrix (29 x 25 named Odour descriptors).

Meta-data – name (Recipe), expressed solely as the fraction of each ingredient, the cultural identity or origin (geographical place or producer) and the base (oil, aqueous, dry, fermented and dairy). A matrix of 29 x 99 variables.

The data blocks are presented in figure 1.

Figure 1: Overview of all data blocks available

By developing new visualization approaches and using tools from data fusion, we analysed, visualised, and explored these complex data structures. We used these tools to investigate the fundamental differences and commonalities in the set of spice mixes. It is a work of very interdisciplinary nature, requiring data analysists, flavour chemists, food professionals and sensory scientists. The process was a feast for geeks, with wild and imaginative discussions, bouncing ideas and swimming in the data. However, the harsh realities hid us hard when submitting the manuscript to scientific journals. Because of the interdisciplinary nature, it was difficult for others to appreciate all aspects of the work, and we had it turned down from four different journals. Finally we had to realise that the ideas and results we presented to the scientific community would not be published in peer-reviewed scientific journals. With this blog post we present you the idea and the concept, and the opportunity to delve deeply into our investigation by reading the full manuscript here, where all details about the chemical and data analytical procedures are available, and the results are discussed in details. In addition, we find that the data are of a unique character. Thus we give access to the data, so that others may use them for further scrutiny. The data can be found here.

Excerpts of results

The projective mapping and the aroma profiling by GC-MS provide two complementary means to quantify the differences between spice mixes, and can be used to perform a combined analysis that shows to what extent sensory results are already contained in the aroma analysis and vice versa. The full data are very complex to present visually, and a low-rank sub-space of the total variation is obtained by multivariate data analysis, Principal Component Analysis (PCA) to be precise. PCA extracts the most important variance in the data, component by component. It allows focus on the most important part of the variance, in the analysis of the patterns of samples and the variables that describe them.

In figure 2, the first two and most important components of the PCA model are shown. These components explain 50% of the variability of the data. In particular, the score plot with all of the samples colored by origin (geographical or developed by), are plotted on the top left corner of the figure (Plot A). Plot B shows the words that the evaluators have used for describing the same samples. Plot C shows a loading plot of the volatile odour compounds. Finally, the recipe plot (Plot D) shows how the mixes can be interpreted on the basis of their ingredients. There is a robust relationship across all the matrices, demonstrating that the different matrices extract similar patterns about the spice mixes.

Figure 2A: Visual representation of the most important variance in the four data blocksSensory map and Sample origin group designated by simlar symbols (origins: Africa; Asia; Britain; Central America; Nordic Food Lab or noma Scandinavia; South America; Southern Europe). See more in full manuscript.

Figure 2B Sensory Words. The descriptors used by the panel to characterise the sensory properties of the spice mixes.

Figure 2C: Odour chemicals and descriptors: The different odorous compounds, and in some cases the sensory descriptors that are known to be associated with the compounds.

Figure 2D: Recipes: Expressed as the fraction of each ingredient, the cultural identity or origin (geographical place or producer) and the base (oil, aqueous, dry, fermented and dairy).

The aroma analysis using gas chromatography (Figure 2 plot C), allows us to dig further into the data. Observation of plot C shows a loading plot of the volatile odour compounds. On the same plot on top of the odour chemicals, the odour descriptors are shown. The plot shows how most of the odours are gathered in the upper-right part of the plot. This can be interpreted as a general trend of increased intensity of aroma, going from the samples in the bottom-left part of the scores plot towards those in the upper-right part. The dry base consists mainly of mixes of pure spices that have been ground up, which contain a high concentration of many highly volatile compounds, e.g. terpenes. The fermented mixes will undoubtedly have a considerable content of acids and umami compounds which are not captured by the GC analysis, but will contribute to the taste of the mixes. The oil-based mixes appear to contain a medium level of aroma compounds, but this may be due to higher aroma retention in the oil under the conditions for trapping the aroma compounds. Finally, the recipe plot (Figure 2, plot C) shows how the paste grouping can be interpreted on the basis of their ingredients. One can see how the ingredients naturally reflect the groupings such as blueberry in the left part, juniper in the upper, and chipotle in the lower part. A very detailed analysis of the patterns is provided in the full manuscript.

ConclusionsIt is a comprehensive way to fuse sensory projective mapping data, gastronomic information (recipes), and aroma profiling (gas chromatographic data). The method also allows for inclusion of additional data if available. More efforts are needed to help minimize the barriers that result from this highly cross-disciplinary experiment. There is a need for the ability to communicate across many fields of expertise such as chemistry, flavour research, gastronomy, mathematics, and sensory science. Finding a common language that allows open and creative communication is of paramount importance for the advancement of the field.

We made a large effort to improve the visualization of the problem by enhancing the readability of the most important loadings in all the loadings plots. However, work is still required and in the future we intend to expand on this, taking advantage of modern tools that computer science offers, such as interactive visualizations that allow a deeper exploration of complex data for which static plots are sometimes inadequate.

Acknowledgements and thanksWe kindly acknowledge the 26 persons that gave their valuable time to evaluate the spice mixes. In addition, we acknowledge noma for the donation of Ants and juniper mix. We acknowledge Kiki Sontiyart, Ana Caballero and Guillemette Barthouil for their contribution to the creation of the spice mixes. And lastly we thank the anonymous reviewers that helped us improve the manuscripts along the way.

Laphet made from young birch leaves, fermented with whey from acidified milk (syrnet mælk)

Burmese people do not only drink a lot of tea, but also eat it. Laphet (also lahpet, lephet, letpet, leppet) in Burmese represents a generic term for fermented pickled tea leaf, whereas laphet thoke/thohk, fermented tea leaf salad, and ahlu-laphet, a laphet snack, are the most common ways to consume laphet (Maung, He and Chamba 2012). Laphet carries a lot of cultural and historical significance in Burma, it is associated with national pride and considered to be a national dish. It is claimed that in ancient times laphet was used as a peace offering or peace symbol between kingdoms at war. In present day Burma, laphet is a habitual dish eaten in various social settings by all Burmese — from traditional ceremonies, monasteries and official celebrations to homes and family get-togethers. It is said that through a laphet tray one demonstrates his/her hospitality towards houseguests (Han and Aye 2015). Burmese also believe laphet to hold health benefits, calling it “Lord leaves” and “Lord Medicine” (Maung et al. 2012). Since it is a staple food, laphet products are found all over Burma; the street stalls in Burmese cities selling plates of laphet thoke are the common manifestations of this food culture (Han and Aye 2015).

With an urge to broaden the knowledge around edible plants and to take up the fermentation of tree and bush leaves in the Lab, in the spring of 2016 I embarked upon an endeavour to replicate laphet using local leaves. At first I chose in-season leaves similar to the tea plant camellia sinensis, with a high quantity of tannins. Over the progression of spring, my local laphet leaf candidates started to successively develop into the right picking condition. Specifically, my intention was to use younger leaves that were large enough to comfortably work with but not yet too fibrous and firm. And so, in three successive weeks, I undertook three foraging trips. Together with Michael I foraged beech leaves from the Ganløse Ore forest, in Værløse, I picked black currant leaves from a farm in Lejre near Roskilde and finally I collected birch leaves from the luscious Amager fælled in Copenhagen together with a fellow intern. Hence, the leaves for my laphet experiment came from very different sources. These leaves held the stories of the places and people from which they came.

The first beech leaves of the season

so tender and soft

Black currant plantation

Birch leaves galore

The process of making laphet

Laphet is produced by anaerobically fermenting tea leaves, resembling the production process of Japanese post-fermented teas awa bancha and goishicha (Shii et al. 2014). The preparation of laphet starts with harvesting and selecting young tea leaves to undergo fermentation. The oxidation of the fresh leaves is stopped by steaming them for approximately five minutes, then water is removed and another selection process occurs. Leaves are then packed into clay pots and pressed with heavy weights to encourage fermentation. At certain intervals, leaves are checked and some additional steaming can be applied. Steaming increases the production of phenolic compounds found in the tea leaf, which, in turn, enable the growth of particular microbes, whereas other unwanted and detrimental microbes are unable to grow even if fermentation is carried out in non-sterile conditions (Han 2015). According to some accounts, rolling the leaves takes place in-between the steaming and pressing stages (Maung et al. 2012). The fermentation takes place due to the naturally occurring lactic acid bacteria (LAB) present on the leaves and in the environment. Some reports claim laphet is fermented in bamboo vats (rather than clay pots) that are placed in pits in the ground (Zafrudin 2010) — this process adds an interesting layer to the fermentation in regards to environment and temperature change.

The laphet pulpsoftens in a few weeks, though there are different accounts of when the fermentation process is complete — from two weeks to three to four months up to a year (Han 2015; Maung et al. 2012; Zafrudin 2010). However, there are certain physical characteristics that imply when the fermentation is ready - leaves start to soften and change colour from green to golden green and the acidity decreases (Han 2015). It seems to me that the aim of the fermentation is not so much to preserve the leaves, though the fermentation process surely enables one to consume the tea leaves over a longer time span. But fermentation is foremost carried out to break down the fibrous structure and to attenuate the bitter taste of fresh tea leaves, while simultaneously adding some interesting flavour and aroma characteristics. In some sense, leaves are made more edible through the fermentation process.

When I designed my laphet experiment, I had to consider that the conditions for processing laphet in Denmark are rather different from those in Burma. Much to my sorrow, the lab context did not really allow me to ferment the laphet in bamboo vats in the ground up to a year… Also, I could not be certain if wild fermentation would start based on the LAB found naturally on the leaves, as it does with the original laphet. I needed to be sure that it is the LAB fermenting the laphet and that some other bacteria will not take over. Therefore, I decided to inoculate the leaves with various sources of LAB, creating five different versions of laphet in each batch. For the different sources of LAB, I used whey strained from syrnet mælk (A) and yogurt (B) as well as some skyrkultur (C) and fermented bee pollen (D) that I mixed with filtered tap water. In addition, I also immersed the leaves in salt brine (E) to create an environment favourable for the LAB. Because the beech leaves gave out enough liquid, I was able to immerse the leaves in their own liquid and thus create a wild fermentation, similarly to the original laphet. The currant and birch leaves were too dry for the same process.

Before the inoculation, I followed a similar procedure with all three batches. I briefly steamed the fresh leaves - thirty seconds for more tender beech leaves, two minutes for more fibrous currant and birch leaves, I then rolled and massaged the wilted leaves and mixed with the different sources of LAB. At that point, I placed the leaves into glass containers and submerged them under the liquid with weights. I checked the progress from time to time, and let the leaves ferment for at least two weeks.

Beech

The bright green fresh beech leaves seemed promising — texturally tender and light, yet somehow resilient; taste-wise pleasantly astringent, resembling unripe persimmon. From the three leaf candidates, they were most similar to the leaves of camellia sinensis. During fermentation, rather strong perfume-like sour and sweet aromas started to develop, with some batches producing some tainted smells as well. In two weeks, the flavours that had generated were mostly strongly acidic and wine-like sweet-sour flavours, sadly the texture that turned out to be unpleasant. Contrary to my hopes of a soft and delicate composition, the tender leaves had dissolved into a puree-like mass, though an unpleasant toughness still remained when trying to chew the leaves. It was clear that consuming beech leaves in a traditional way (such as mixed in a salad) would not work, so I decided to experiment with a different approach. I took the beech leaves that I had fermented in salt brine, I rinsed them to remove a bit of the saltiness and pounded the leaves into a paste together with some typical Burmese flavours such as fresh ginger, fresh garlic, and chilli, while also adding some oil, soya and rice vinegar to enhance the texture and flavour. It turned out to be a potent sour-spicy paste that could be served as a condiment to grains and certain vegetables. Perhaps a more mildly flavoured sour paste from the fermented beech leaves would work as a condiment for fresh cheeses like burrata. Still it must be pointed out that the leaves which at first seemed most promising, actually turned out to be the least interesting in terms of flavour and most problematic in terms of texture.

Fresh tender beech leaves

Steamed beech leaves

Rolled steamed beech leaves

Beech laphet paste

Black currant

Compared to the beech leaves, fresh black currant leaves had a tougher texture, were more fibrous and rather dry. They released little moisture even after steaming and rolling. Their aroma was straightforward of black currants, even more so after steaming. Though by the fifth fermentation day, the black currant aroma was replaced with cloying or in some cases more complex sweet-sour smells. Two weeks after the start of fermentation, a mellow and more complex currant-like character returned with some other intriguing aroma and taste advancements. In fact, how the collected leaves reacted to the different LAB sources and made the flavours and smells of the leaves transform during the fermentation, was beautifully demonstrated with the black currant leaves laphet batch.

Fresh young black currant leaves

Steamed black currant leaves

Rolled steamed black currant leaves

Fermented black currant leaves

Consider the black currant leaves fermented in syrnet mælk whey. After two weeks, the flavour could be characterised as fruity and sour in the beginning and metallic towards the end, resembling green unripe strawberries or juicy green peaches. The aroma, in turn, elicited savoury vegetable notes, reminiscent of green chilli peppers. Moreover, the fibrous texture of the currant leaves had remained but also transformed into a state where the leaves were simultaneously firm and half-way soft, thus pleasant to chew and fitting well to be incorporated into a simple fresh salad. The currant leaves fermented with yoghurt whey had a pleasant fibrous and dense texture, encouraging the eater to work with her or his teeth, or, ‘get back the bite’ as one taster fittingly commented. The same person also reported an experience of a long progression of tastes with this laphet version - from bright sour to tingling sensations to metallic and mineral notes, overall reminding him of the experience of eating grape leaves.

There was one more black currant laphet version — black currant leaves inoculated with fermented bee pollen where the flavour profile showed good potential, with notes of apricot, melon, capers and cucumbers. However, the texture of the leaves maintained a disturbing fibrousness. For this, an idea was born to develop the texture further. I detangled and dehydrated the leaves overnight. The result was sour and tender black currant leaf chips, extremely crunchy and subsequently melting in the mouth. Contrary to the freshly fermented leaves, where the acid came right at the beginning and then softened in complex ways, the dried leaves had almost the opposite effect — first you got the texture, it then disintegrated a little bit on the tongue and then a delayed flavour burst followed.

These acidified dried black currant leaves were ideal to use in a Nordic furikake. Furikake is a dry Japanese seasoning consisting typically of chopped dry seaweed, sesame seeds, dried and ground fish and some salt and sugar. It is usually sprinkled over cooked rice, vegetables and fish. At the Lab we mixed the laphet leaves with some dried and grated deer leg for umami taste and some buttered buckwheat grains for texture, while also adding a bit of salt. The Nordic furikake turned out to be a delicious condiment to be sprinkled on top of rice or local fresh potatoes.

Dehydrating fermented black currant leaves

New potatoes in a Nordic furikake made from dried black currant laphet leaves and buttered buckwheat

The black currant leaves that I had fermented in salt brine also responded well to dehydration, changing into salty-sour leafy and crunchy chips. While still preserving their leafy and woody character, they were enhanced by drying, evoking associations from commentators such as ‘a leaf that might have been sitting on top of a cheese’, referring to the umami taste the leaf acquires when wrapped around some flavourful cheese.

Salty-sour and umami-rich dried black currant leaves on cheese

The conclusion from the tastings is that the black currant leaves which seemed rather one-dimensional while fresh, transformed after fermentation into a complex mixture of flavours, tastes and textures, with options to choose between different courses of action when processing to optimise them for different gastronomic purposes.

Birch

Fresh birch leaves were light and soft, though it is important to emphasise that I picked spring leaves that, although fully developed in size, were still young and tender. Birch leaves, similarly to currant leaves, were also rather dry and somewhat fibrous (especially compared to the beech leaves). Though in most birch laphet versions, the fibrousness of the birch leaves disappeared during the fermentation and a firm leafy texture remained, enabling a soft, yielding and pleasant bite. The bitter taste of fresh birch leaves faded as a consequence of the fermentation, making the birch leaves great candidates for salads replicating original laphet consumption. Although there were also some birch trials (e.g. birch leaves with salt brine) that elicited some peculiar sensations, such as foamy and soapy sensations in the mouth as well as associations to licking a battery – the sensation of low-current electricity, or from gastronomic origin, that of Sichuan pepper (seeds from threes of Zanthoxylum genus). Birch leaves fermented with bee pollen even evoked feelings of pain in the sides of the mouth of one taster; he associated it with strong fermented foods that make him feel agitated, excited and hot.

Fresh birch leaves

Steamed birch leaves

Processing birch leaves

Fermented birch laphet

The best among the birch laphet batches were definitely birch leaves fermented in whey from syrnet mælk. These leaves were beautifully balanced, ticking the acidity, texture, aroma and fruitiness boxes. The texture was slightly slippery yet still with a good bite; the taste was fruity – reminiscent of sour cherries. I used these birch leaves to make our own version of the laphet thoke, the traditional Burmese tea leaf salad. Laphet thoke is a balancing act of tastes and textures, interweaving earthy, tart and spicy taste notes together with chewy, soft and crispy textures. This is what I aimed to achieve when mixing the pungent leaves together with some roasted garlic slices, pickled ginger stripes, sliced broccoli stems, boiled chickpeas, sesame seeds and fermented green chillies, while flavouring the salad mixture with fish sauce, lime juice and sesame oil.

New book by Nordic Food Lab - Available for pre-order now

On Eating Insects – Essays, stories and recipes. A book by Nordic Food Lab published by Phaidon available for pre–order now.

Insects have been the center of many of our activities during the last years. In May 2016 we finished the Velux-funded project ‘Deliciousness of insects’, and naturally there has been many outcomes from that in the recent year - talks, press, publications, and very importantly a feature length-documentary film BUGS by Andreas Johnsen.

The last milestone we lay down for the project is the publication of a book. On eating Insects – Essays. Stories and recipes. The book is published by Phaidon, and it will be out in bookstores May 1st. It can be pre-ordered from the publisher through this link, or from major retailers. We list Nordic Food Lab as author, as we find that first and foremost this book is a result of the lab's work. We know that this is not the conventional way of authorship. The authors from the lab are Josh Evans, Roberto Flore and Michael Bom Frøst. Many other people contributed to the project and we are genuinely thankful for their work. This brief blogpost is not the right place to list all of them - they are mentioned in the book. But in particular we need to thank Chris Tønnesen for the beautiful images, Rene Redzepi and Mark Bomford of Yale's Sustainable Food Program for writing foreword and introduction. Lastly we thank our editors at Phaidon, Sophe Hodgkin and Ellie Smith.

We really look forward to bring this book to the world.

The end of the project also meant that Josh moved on from the lab after being four years with us. We wish him all the best with his future studies at University of Cambridge.

The Nordic Food Lab will continue to investigate the gastronomic potential of insects in the coming years. Michael and Roberto will be involved in a new large insect project - InValuable - with many partners in Denmark and abroad. Here our role is smaller but as essential – the creation of delicious insect foods.

Jonas started helping out at the lab informally back in 2010, and while he was completing his master's studies he did his project-in-practice on kombucha and a bee larvae consumer acceptance study for his thesis. He joined the lab as staff in July 2014 to head up our contributions to the Smag for Livet project; now, he'll be working with the Meyer group on product development.

Josh came to the lab as an intern in June of 2012, and was hired one year later when we gained three years of funding for our insect research. This project is just wrapping up, and while we will continue to work with insects, Josh will be moving on to begin post-graduate study in England in the fall.

We thank both for their multiple contributions to our work, and we wish them all the best for their future investigations, and much continued deliciousness.

Last week, our documentary film BUGS, directed by Andreas Johnsen, had its world premiere at the Tribeca Film Festival in New York.

There were four screenings, some great Q&A sessions, many press interviews, and two pop-ups—the first with escamol ice cream served on the High Line, the other with escamol tacos served at Miscelanea, a self-described Mexican general store in the East Village. Both were made possible by José Carlos Redon and his brother Alessandro, who helped us out with our fieldwork in Mexico in March 2014 and flew up to NYC for the premiere—with 10kg of escamoles no less!

Many thanks to Andreas, Peter, and everyone at Danish Documentary for making it a thrilling and successful week.

The film will be having other continental and national premieres over the coming months, so stay tuned for news here and over on bugsfeed.com, the website for the film. Until then, here is the official trailer.

I like tea. I like how one plant becomes many different kinds of drink. I like that one can cultivate the craft of brewing it, as well as just enjoy it simply. I like that it has rituals, and its psychotropic effects. I like that lots of other people like it, but not everyone likes it the same way.

This is a 3-years-long story about tea and tea-like non-teas. But it didn't start with tea. It started—as more than a few of our projects do, it seems—with a fungus.

Part 1—A. niger and Pu-erh

Meet Aspergillus niger. Yes, it is part of the same genus as our homeboy A. oryzae. But the similarities largely stop there. While the koji mould is white, for example, this one, as its name suggests, is black. And while koji mould is used for making all sorts of fermented products like miso, soy sauce, sake, amazake, shio-koji, and others, A. niger occupies a very different edible niche. In many cases, actually, A. niger is seen as an agricultural pest. It's quite ubiquitous across all sorts of soil samples. Yet for a certain type of tea called Pu-erh, produced in Yunnan province in the south of China, A. niger is one of the process' key microorganisms.

Most teas, it turns out, are not strictly speaking 'fermented'—that is, their transformations are not the result of microbial metabolism, but rather variations of oxidation, autonomic or enzymatically facilitated, modulated by physical techniques of wilting, steaming, panning, baking, rolling, drying and others in a great many combinations.

A flowchart of tea processing that simplifies a much more complex combinatorial range of methods. (Wikipedia)

That's where the Pu-erh comes in. This tea does involve microbial metabolism—after undergoing some of the first steps that usually lead to green tea, the partly-processed leaves are heaped into piles and let to spontaneously ferment. A. niger comes to dominate and contributes prominently to its flavour, adding notes of earth, moss, and cellar to the mix (geosmin is one of its main secondary metabolites), while rounding astringency and smoothing bitterness. It brings a particular perspective to an already complex product—the result is something that, unlike many teas which begin to deteriorate as soon as their processing is complete, can be aged for ten, twenty, thirty years or more, increasing in complexity and nuance, and demanding even more when it comes to brewing and drinking it best. More like a wine than an olive oil. A pu-erh-obsessed friend of mine in Japan, Max McCurdy, brewed us some while I was in Tokyo in November 2014, after our insect field work. He had a tiny teapot, one that could fit into the palm of my hand; we only started drinking from the third brewing, and kept drinking until well after the tenth. It is, in my experience, a particularly convivial way of drinking tea, as it demands repeated motions of boiling, brewing, and pouring that become perfect punctuations in a long, slow-burning series of shared caffeinated jaunts.

Max's tiny pu-erh pot being drained for drinking

January 2013 is when I first started looking into microbial action in tea. Mycotoxicity in many fungal species can vary according to the strain and growth conditions, but with a bit of research I learned that A. niger is generally safe for human consumption (Blumenthal, 2004). I first met A. niger in person in February, after our friend and fellow fungal enthusiast Sara Landvik, a researcher at Novozymes, graciously agreed to plate me a couple known strains from their open collection. I propagated them on some standard PDA plates we had already prepared (petri dishes with a simple mixture of potato starch and dextrose in an agar gel), and planned the plants I would try to encourage the fungus to ferment into some sort of pu-erh-like tea.

Here are my notes from trials over the 2013 growing season.

12.2.13I began with A. niger plated up by Sara Landvik, our friendly microbiologist at Novozymes, replated it to multiple plates, let it sporulate, then mixed the spores into sterilized water, and steeped dried verbena leaves in a small amount of liquid inoculum to coat and absorb. They are now slowly drying.

Lemon verbena pu-erh

8.7.13The verbena pu-erh has been sitting for months and is still very fragrant - earthy and complex.Now we are in the season of growth. I have begun trials with elderflower, jasmine, nettles, beach rose (pink and white), dittander (leaves and flowers). Going to look for fireweed (Chamerion angustifolium) - similarities to Camellia sinensis.I've put the A. niger inoculum into an atomiser.

Elderflower (Sambucus nigra)

Elderflower - I sprayed some whole on the stem and also loose, and left it out at room temperature on a plate. I also blanched a few heads then inoculated and left them out. The blanched ones have turned a dark green with black tips and a stronger smell - the rupturing of the cells seems to enhance the enculturation, even beyond the oxidation.

Jasmine

Jasmine - I harvested some jasmine from the tree at my house. Should figure out which species it is. Now with the more delicate flowers I have started using the vacuum packer to vacuum impregnate the cells with the liquid inoculum, instead of blanching. It also helps speed oxidation. After three days of drying the vacuum-impregnated flowers are noticeably darker and more aromatic.

The compressed jasmine (L) became slightly darker and gained a deeper, smokier smell than the uncompressed (R).

Nettles - I rinsed dry whole nettle leaves in water to soften, then tossed them gently with the liquid inoculum.

Nettles (Urtica dioica)

Beach rose (Rosa rugosa)

Beach rose - Pink and white. I separated loose petals and whole blossoms, and again did half just spray and half sprayed then vacuum impregnation. Not so much difference here yet but we will see.

Justine with flowering dittander (Lepidium latifolium)

Dittander - the leaves and flowers are still drying - they are quite sturdy, perhaps too much so for this processing. The flowers smell mainly of hay. The leaves look somewhat promising - but next time I should rub them between my hands more vigorously to get the oxidation going, before continuing the process.

Processing the dittander

Dittander flowers and leaves

12.7.13The flowers are becoming more fragrant.The dittander doesn't oxidise fully when bruised. It ends up just losing most of its pungency and drying out.The nettles are promising - they oxidise very well, and gain fantastic aroma.

Finished nettle tea.

25.7.13Justine found fireweed in Charlottenlund on Tuesday 23.7. I stripped the leaves that evening, rolled and pressed them to break the cells and begin the oxidation. I kept them in a plastic container until Thursday evening. They generated humidity and began smelling strongly: overripe mango, feijoa, curing apple, bubblegum, terpinic, guava, green, juicy fruit apple, hay, grass, summer, benzyl anthranilate (grapefruity/tropical flavours). Thursday evening I spread them out to dry and continue oxidising on the counter. Friday morning I sealed them in vacuum bags to ferment anaerobically over the weekend.The half kept in the box retained its fruity, berry aroma, while the one left to dry open had these fruity notes replaced with more green, fresh hay, green banana.

29.7.13Both bags when opened smell strongly of olives and pickles - very lactic and savoury. This mellows quite quickly.I split each batch (aired/sealed) into two, toasted half in a pan until just before crisp and the other steamed in the oven, both to halt the fermentation.The toasted ones smell like: 'roasted pineapple' (Sarah), 'herbaceous and green' (Avery), 'vinegar sauce' (Justine), 'sexy'/'arousing' (Ben)The steamed ones smell like: 'banana' (Sarah), 'olives'/'some sort of piss' (Justine), 'capers'/'marine'/'piss' (Ben)The dittander has since turned into vomit; they can be forgotten.

4.10.13Finally a sensory.First the flowers - beach roses (white and pink), and jasmine. 1.2g/120ml water (80˚C), 4 min infusion. The roses are both weak and insipid, but the jasmine has potential - smells of old leather, smoke, old perfume. It is grown-up. A stronger extraction could help, and perhaps a tincture.

Lemon verbena was also worthwhile—its aromatic top notes became subdued and gained a grown-up richness not usually present in the herb, fresh or dried.

Next, the original lemon verbena. 2.4g/120ml water (80˚), 4 min. infusion. Multiple infusions as follows:1st. Musty, woody, mouldy. It smells rounded, the similar sensation of smelling cold cream. The taste is unbalanced and fuzzy, not unpleasant but neither so pleasant.2nd. It is stronger - leather, cedar; the mustiness accumulates with sips.3rd. Smoother, rounder. This is good.4th. Has body, grown up. The cedar comes forward.5th. The sweetness of the verbena now really comes through, and the wood. It is brash, past. It will only weaken and simplify.The third and fourth trials were the best.

The nettle became rich and savoury - successful, though perhaps more suited to a broth than a tea.

Then fireweed. There are six trials: two parameters of fermentation start ('aired/sealed') and stop ('air-dried/steamed/toasted').The toasted ones are very smoky - only the second brewing was remotely palatable, the first too brash, the third already stale. Shall I toast differently?I prefer the steamed - the air-dried are olivey, too vegetal. The steamed are delicate with good balance and light body for me.Others liked the air-dried, perhaps for the particular aromas.Overall I think I prefer the sealed ones - the flavour is stronger and more complex.

For next season, focus on fireweed, and inoculate with A. niger.

12.6.14I learned from Sara that A. niger is fond of higher temperatures, 30-37˚C.

While some of these applications were interesting and potentially useful for something, they did not get at the heart of the matter—which is to say that I still wanted to drink some tea, and I wasn't yet there.

Part 2—Fireweed

At this point I need to depart temporarily from pu-erh, and focus in on fireweed. Ben had found an entry in a Swedish herbal about how people used to make tea from fireweed, and sent it my way. I made first fireweed trials that summer of 2013, and promptly fell down the fireweed hole.

It turns out fireweed has quite a lot to do (culturally at least) with the tea plant, that is, Camellia sinensis. Fireweed tea was also called Koporye tea in Russia, after the area of Koporye west of St. Petersburg near the Gulf of Finland, where in the 1800s producing fireweed tea was the main source of income. Inhabitants of this region even burned forest in order to stimulate the growth of the plant. It seems that despite not containing caffeine, the sensory properties of fireweed, properly processed, could become so similar to Chinese tea made from Camellia sinensis that it could be and was used in place of the real thing. Some unscrupulous merchants are reported to have cut their imports of 'real' Chinese tea with up to 40% Koporye tea, which was only discovered once their accounts showed they had sold twice as much tea as they had imported! (Ljungkvist, 2011)

Here was a plant with some proven potential. Fireweed's binomial is Chamerion angustifolium, formerly Epilobium angustifolium. The Chamerion genus has eight species, all of which are perennial and restricted to the northern Hemisphere. C. angustifolium and its close relative C. latifolium are circumboreal and circumarctic, while the six others are native only to Eurasia. Like many 'wild' plants fireweed has a great many vernacular names: willow herb, blooming sally, purple rocket, rickup, wicopy, and many variations on the theme. And that is just English—there are supposedly over 85 different names for the plant in Swedish (ibid.).

Fireweed is a robust perennial, growing .5-3m tall. It has fine roots and rhizomes, extending down to 45cm in the soil, purplish stems, narrow leaves around 3-20cm long, pink/magenta four-petalled flowers ~2-3cm in diameter, and long slender fruits of a similar colour to the flower. In late summer when the fruits dry they burst open and release long-haired seeds to the wind. The plant can reproduce both sexually (through flowering) and asexually (vegetative reproduction through rhizomes), depending on climate and environmental pressures. So awesome! Imagine if we could do that.

In addition to the leaves being used for tea, different parts of the plant have been used for food and medicine by people around the Northern Hemisphere where it is found: the young shoots as a vegetable similar to asparagus, the young leaves as a green, the roots as another vegetable and sometimes roasted and brewed as a coffee substitute (best before the plant flowers), the flowers made into jelly (ibid.). The plant has been used in both European and North American folk medicine traditions to soothe skin irritation and burns, and brewed into a tea to relieve stomach upset, respiratory difficulties, constipation, prostate conditions and urinary difficulties (PFAF, 2012). There is even production of monofloral fireweed honey in Alaska, as well as reports of an ale made with fireweed in Kamchatka, whose intoxicating factor was bolstered with the addition of the hallucinogenic fly agaric mushroom Amanita muscaria.

Other non-edible uses include cordage from the fibre of the outer stems, stuffing material and tinder from the seed hairs, and a protection from the cold from the powdered inner cortex when applied to exposed skin. At one point some enterprising Swedes tried to make a cotton-like textile from the fibrous seed hairs, but it didn't work so well (Ljungqvist, 2011).

Fireweed is common in a variety of ecosystems: by streams, in uplands, coniferous and mixed forests, aspen parklands, grasslands, and bogs. It quickly colonises disturbed habitats, such as logged areas, deglaciated land, avalanche zones, highway and railway embankments, old fields, and burned areas (hence 'fireweed'). During the Second World War, fireweed also came to be known as ‘bombweed’ due to its proliferation in bomb craters. The plant can handle shade but grows best in open locations with direct light, and prefers acidic soil. It is easily cultivated, growing best in soil with good drainage but that also retains moisture, yet it can also grow in many other conditions. It is hardy to -20˚C. Fireweed is currently only cultivated as a soil stabiliser, and because of its widespread distribution across the Northern Hemisphere it is quite easily harvested locally, including in Denmark and Scandinavia.

Fireweed after a forest fire.

I learned about fireweed in the middle of the summer 2013, too late to work with the tender young shoots and barely catching the end of the younger leaves—the best candidates for making tea. The younger leaves can be quite delicate, with a bright, fresh-olive aroma and a slight bitterness. The flowers are gently fragrant with a hint of sweetness. When oxidised, the leaves take on a dark colour and various notes of black tea and fruit. When fermented, they develop notes of fermented olives and brine. I began working with more mature specimens to get a feel for the plant and how it responded to the technique, making trials on how to initiate, direct and stop oxidation, and bode my time until the following season.

At the end of the summer, I took a trip to the Danish island of Bornholm with my friend Josh Pollen (he's a chef in London who runs Blanch & Shock together with his partner Mike Knowlden, and he's spent sometime with us before). We spent three days biking around the island, eating mirabelles, getting lost on logging roads, and camping on the beach. It is a beautiful island.

Josh chilling in a sea of wood sorrel

On our last night, we went to Kadeau Bornholm, the first time for us both. After our meal, we hung out with some of the team, and when we told them we were sleeping in the beach dunes below the restaurant that night they invited us to staff breakfast the following morning. After breakfast, Markus Junkala, one of the sous-chefs who has since become a great collaborator, gave us a tour and showed us a bunch of things they were working on, one of which was——fireweed tea! The coincidence was too funny. We agreed once the season had finished on the island, we would meet back in Copenhagen and plan some collaborative R&D for the spring.

Part 3—Making tea

At the start of June 2014 I went to Bornholm to work further with Markus on developing a fireweed tea we wanted to drink. Here are my tea-related notes from that time.

6.6.14tea - focus on fireweed. start with oxidation, develop technique. then layer A. niger on top. to serve alone, in a blend, and also to make a variety.

Markus leading the way to forage beach coriander.

Fireweed leaves stripped from the stem

7.6.14fireweed. harvested kl.930. left in plastic garbage bag all day to begin to wilt. picked leaves at kl.18, crushed by hand, oxidation begun kl.19. bashed with rolling pins in gastros kl.23 to increase oxidation (the kitchen guys thought we were crazy).The plan for the fireweed is to do a bit more of a structured process, to figure out what we think works best. So far, our variables are:fermentation method: under weight, under vacuumfermentation time: 2 days, 3 daysfermentation halting method: dehydrating, sun-drying, steaming, roastingThis matrix yields 16 trials.Other possible variables to explore include oxidation method, oxidation time, fermentation temperature, storage method, and post-fermentation moulding with A. niger.

Over those few days in June the weather was glorious, sunny and hot—hence our optimism and excitement with being able to use sun-drying as a processing method. On Tuesday the 10th and Wednesday the 11th, however—the days Markus was to halt the fermentation—the sun had disappeared, so he removed the 'sun-dried' variable from the trials. Which was just as well because nine trials was enough for one tasting, let alone sixteen.

15.7.14[This day we conducted a tasting trial, along with Nicolai, Magnus and Rasmus, the trio behind the restaurant. We also began applying the techniques to plants other than fireweed to see what happened]tea taste trial. 8 fireweed trials + 1 just lightly oxidised version:

Trials for double-blind tasting 1, July 2014 at Kadeau Bornholm, with unfermented control (#9). Two brewings were tasted, and none from the second were preferred. If only I knew how to represent matrices in three dimensions, it would be much prettier..

Bashing fig leaves with a rolling pin. A bit crude, but it was a first trial..

trials 1 and 7 are best for further development, as well as 2 and 9. It seems the non-vacced are preferred, with the steamed preferred at 2 days and the roasted at 3. [This could be because the container-fermented leaves have more internal variability and thus develop a greater range of flavour, whereas the vacuum-sealed leaves have quite a consistent environment and so the range is more narrow.. just a hypothesis.. in any case the more delicate flavour after 2 days makes more sense for steaming, and the stronger flavour after 3 for roasting. The best steamed trials were appreciated for their balanced taste and herbal/floral notes, while the best roasted trials were enjoyed for their fuller tannins and noted similarity to earl grey.]processing other teas: fig leaf, kohlrabi leaf, meadowsweet leaves, angelica leaves, tansy leaves. started oxidising, and fermenting at end of night.

17.7.14teas - more control trials of lightly oxidised then dried/steamed; and further trials with the flowers: with leaves included during oxidation/fermentation, as well as excluded, dried and then added to the processed tea.other teas: post-fermentation processing for fig leaf, meadowsweet, tansy, kohlrabi. the kohlrabi is disgusting and farty and rotten - tossed. the meadowsweet isn’t so fermented, it is quite sturdy - sealed full and kept longer.

11.11.14TEA TASTING:

Trials for blind tasting 2, November 2014 at Kadeau København. Two brewings were tasted. All trials had standard 2-day fermentation in container.

brewing method: 2.5g in bag / 100ml, pulled at 1 min; re-brewedResults:with flowers - we seem to prefer roasted ones (batches 5 and 8), as well as batch 6, with dried flowers added after fermentation and drying. in general, those processed with flowers (3-5) get too soapy. 6 may be better in second brewing, lactic notes are more mild. otherwise, 1st brewing is best and very aromatic.meadowsweet - 9 (ofd) is best. the others lose the meadowsweet flavour. perhaps needs less processing eg. only 1 day fermentation.fig - 12 (ofd) is horrible; 13 (ofsd) is better and preserves some of the fig/coconut flavour. none are good enough by themselves, maybe blended with other teas, and/or with fresh leaves. or maybe tincture is just better for the fig leaf!tansy - amazing smells! all so incredibly bitter! perfect rotovap potential, to separate the top notes from the bitter taste compounds.angelica - definitely savoury broth territory. 19 (ofsd) and 20 (ofr) are best, and give a fantastic tingling sensation. could be great mixed with fresh/dried angelica leaves for more of those angelica top notes. these have loads of body. use with something fatty! like pork, or lamb neck.

By this point we had gained a few different directions to take the research: developing a tea to drink, especially as a post-prandial; and using a similar technique to supercharge the flavours of many different plants for savoury applications—especially plants, like fireweed, that don't have so much flavour in their raw form, or have a nice aroma but a tough, sturdy, or fibrous texture that does not lend the leaves well to being eaten directly, either raw or cooked (like fig leaves, and mature leaves of tansy, angelica, meadowsweet, and many others).

And now, at last, a recipe. Here is the protocol Markus and I developed for a basic fireweed tea, which can be conjugated further for all sorts of other plants.

Fireweed tea

1. Harvest a bunch of fireweed. Cut the stalk just below the last useable leaf—depending on the fineness of the tea this could be anywhere from just the tip to the tenth leaf or more.2. Pick. Bring the fireweed back to your working area. Pick off the leaves from the stem, and, if wanting to make different grades, sort into different sizes. Discard any leaves that are brown, dried, or otherwise not intact.3. Oxidise. Depending on the amount of leaves and available time, this can be done by rolling and/or crushing the leaves with one's hands, bashing them with a rolling pin in a gastrotray, or other methods which we invite you to dream up.4. Develop flavour. Let the leaves sit to oxidise and develop flavour—this length of time can be however long or short one prefers, although we tended to let it go for at least a couple hours and no more than twelve. We found the tea turned out best when the oxidising leaves were at the height of aromatic intensity.5. Ferment. Put the oxidised leaves into a container and place another container of identical size on top, pressing firmly so the leaves compact and become more or less 'sealed' in the bottom container. Allow the leaves to ferment at ambient temperature for 2-3 days (or less or more) depending on the plant and the desired result.6. Halt fermentation. Once the leaves have fermented, remove from the container and halt the fermentation by dehydrating, steaming, roasting, or any other technique you prefer for dispatching bacteria (except maybe not bleach).7. Store. Once the fermenting leaves have been turned into non-fermenting leaves, ensure the leaves are sufficiently dry and have cooled to ambient temperature, then store. We prefer sealing at partial vacuum (to remove as much air from the bag as possible without crushing the leaves) and keeping cool and dark, to prevent further oxidation from light, heat, or oxygen or from taking up other unwanted aromas.8. Brew. The standard procedure for (black) tea sensory analysis (I have since read) is 3g of tea to 150mL boiling water, infused for 5 minutes then poured for evaluation (Kan et al., 2004). Of course, one may brew the tea however one may wish, which will also change depending on the processing method (we have found toasted/roasted teas can handle higher brewing temperatures), the desired profile, and the culinary function.

Future things to test:- separate fireweed leaves into different grades depending on the size and conditions of harvest, as do producers of high-quality tea- sun-drying versus dehydrating to halt fermentation- different oxidation methods- different oxidation times- different fermentation temperatures (all of these trials were conducted at warm summer room temperature, mid-to-high 20s)- different post-processing storage methods (these trials were sealed with a partial vacuum and stored in the freezer)- try all sorts of tough plants with flavour potential, especially parts of plants often thrown away like tough parts of leeks, tomato leaves, etc.- and last but not least, now we have a method to which to add the extra layer of fermentation with Aspergillus niger! I want to make fireweed Pu-erh, build a pressing mould and press it into bricks, age it and see what happens—that's what's next..

Fireweed outside the window of the train, north of Copenhagen. Now I see fireweed everywhere I go..

Acknowledgements

Many thanks to:Sara Landvik for plating up our sources of Aspergillus niger;Josh Pollen as the quintessential comrade;Markus Junkala for being a brilliant partner-in-crime;Nicolai Nørregaard and the whole team at Kadeau for hosting me and giving me and Markus time and space to carry out our research on Bornholm and in Copenhagen;Max McCurdy in Tokyo for that memorable pu-erh-fueled evening in November 2014;and of course many members of the NFL team past and present.

Blend insects until broken up but not into a smooth purée and keep in a container. Mix insect purée, barley, water and salt together. Place in a non-reactive container with cling film directly covering the surface. Place container in a 40˚C incubator or suitable area, and allow at least 10 weeks to ferment. The garum will separate and remain on the bottom of the vessel, and should be decanted/siphoned with an appropriate pipette/tube. The paste is also excellent, and should be passed through a fine sauce net.

In the summer of 2013, we began to make two 'pressings', as one does with olive oil. The first 'pressing' involved filtering the fermented mixture through a filter paper solely by gravity, obtaining a translucent liquid with few impurities—we called this 'Extra Virgin Grasshopper Garum'. The second pressing actually involved some real pressing, where we took what remained in the filter and pressed it through a superbag to obtain 'Second Press Grasshopper Garum', analogous in some sense to pomace oil.

Extra Virgin Grasshopper Garum on the equator in Uganda.

Last summer, in 2015, we took things a bit further. Firstly, we made production batches of five 'single-species' garums using the same basic recipe as the original, and only one species per batch (based on trials we had conducted the previous summer, in 2014). The species were: grasshopper (Locusta migratoria), cricket (Acheta domesticus), wax moth larvae (Galleria mellonella), bee larvae (Apis mellifera), and mealworm (Tenebrio molitor).

When it came time to filter, we realised that we could go into more detail than we had before—particularly because we had Bernat's PhD rigour with us, and were thus well-positioned to go deeper into the post-fermentation part of the process.

We began with the complete garum mixture, post-fermentation. We passed this mixture through a chinois without filter paper, to begin to separate the liquid and solid phases. We then let the liquid phase pass through filter paper by gravity, yielding a fine liquid that had passed through the paper and an emulsion left on it, which we suspect contained residual compounds and water suspended in fats. The filtered liquid we allowed to further separate into lipid and water phases, yielding 'Virgin Oil' and 'Insect Garum 1st fraction' respectively. We passed the emulsion left in the filter paper through a sauce net and called it 'Paste B'—because we were not expecting to have it and had already named its analogue 'Paste A'.

Fractioning garums by gravity through filter paper.

Meanwhile, the solids reserved from the very first filtration through the chinois we pressed through a superbag, yielding a cloudy liquid, and a bit of solids—mainly chitin, small bits of barley etc.—that we discarded. The liquid we then let pass through a superbag by gravity, yielding a more opaque liquid than the 1st fraction, which we called 'Insect Garum 2nd fraction', and an emulsion left in the superbag that we called 'Paste A'.

We also tried using a vacuum filter to extract more of the liquid, but that didn't end up working so well..

Bernat and the vacuum filter. We had high hopes.

Bernat and Roberto try to collaborate with the vacuum filter

Good old gravity took a bit longer but yielded a better product.

Thus, in total, we obtained five products from this fractioning process: Virgin Oil, Garum 1st fraction, Garum 2nd fraction, Paste A, and Paste B.Our more rigourous fractioning also gave us higher total yields—see Table 1, which does not take into account the Virgin Oil or Pastes A and B.

Table 1. Garum yield as a function of total starting mass. Does not include yield of Virgin Oil or Pastes A and B.

Most importantly, the single-species garums are delicious (except for the Mealworm, which is quite thin and unremarkable) and distinct from one another. We are keen on experimenting further with the pastes, which are just as distinct in taste as the garums—they range in colour from pastel peach to ombré ochre, and some of them have a unique, silky texture. Tobyn started working on some compound butters; we can imagine particular pastes being well-suited to different particular applications.

The range of pastes.

Now the next step is to re-obtain a centrifuge and take the fractioning further—and to see for what, if anything, we can use the discarded fragments of exoskeleton..

4 October 2012—the day before Ben and I departed on a research trip to the Netherlands, we took a bunch of kojis we had made from different nuts, seeds, and grains, cooked up a bunch of pulses, raided our dry store for aromatic things, boiled a big pot of brine and bashed together a bunch of sauces to start fermenting. The method was deliberate madness, mixing and matching kojis, cooked pulses, aromatics and brine in ratios that seemed to work based on similar previous trials and tasting as we went. Textbook shotgun approach.

Three months later, in January, we had a tasting.

Of the twelve trials, we kept seven that had further potential and tossed five that were horrid. One of the former was particularly exciting—it was unmistakably reminiscent of foie gras, with that fatty, nutty taste and rich mouthfeel, and made only of plant-based ingredients. We called it 'faux foie'.

Combine in a sterilised container. Cover the surface of the mixture with plastic wrap and store for three months.

Since then, we tried to take the recipe further by tweaking the quantity of morels and trying out different types of barley for the koji, but we weren't able to achieve the results we were looking for.

We went back to try to replicate the original recipe, even using the remaining amount of the original batch to inoculate the new trials, and still weren't able to reproduce it exactly. Such is the nature of serendipitous success I suppose. We will keep trying.

‘2% salt’. How many times has this phrase passed our lips? By the summer of 2013 we were realising that this simple edict, the core of many lacto-fermentation recipes, contained a crucial ambiguity. This post is an attempt to explore and clarify how different cultures—namely, those of the kitchen and the laboratory—measure things differently, and why it matters.

The problem

Many of the recipes and processes we talk about on this blog scale according to ratios. For example, for a typical lacto-fermentation, rather than starting with 1000 grams of vegetables and 20 grams of salt, it is simpler to weigh the vegetables you have and add 2% salt to them.

But what do we mean when we say “2% salt” or “25% sugar”? A chef might, when presented with 1000 grams of something to which they need to add 25% sugar, add 250 grams of sugar—since 250g is 25% of 1000g. On the other hand, to a scientist, a mixture of fruits with 25% sugar isn't 1000g of fruits and 250g of sugar, but a mixture where 25% of the total weight issugar: and if you started with 1000g of fruit, this total mixture will weigh 1333g and have 333g sugar in it, since 333/1333=25%. In fact, the mixture of 1000g of fruit plus 250g of sugar now only contains 20% sugar by composition, since the total weight is 1000g+250g=1250g, and 250/1250=20%. This difference could lead to problems if the 25% level of sugar was very necessary to reach!

And, unfortunately, while this gap is negligible for small percentage additions—taking “add 5% salt” to mean adding 50g of salt to 1000g of something will yield a mixture that is 4.76% salt by composition, which is pretty close—it gets bigger and bigger as the desired percentage increases, so the potential for error gets increasingly larger as the amount to add goes up: 10% vs. 9.1% is maybe not so big (maybe), but 35% vs. 25% definitely is pretty big.

Terms

As we mulled this problem over, different ways of representing this distinction emerged.At the core of the issue is the relationship between the parts of a mixture and the whole. What varies is the relation’s direction—whether one is going from the former to the latter or vice versa.

1. ‘Process’ vs. ‘Product’Our first framework for conceptualising this difference was ‘process’ vs. ‘product’: ‘process percentage’ for the easy-to-use number of what you actually need to add, in terms of the weight of what you are adding it to; and ‘product percentage’ for the percentage of what, by mass, is actually in the final mixture. These words capture the distinction neatly, but they may not be different enough to make an elegant notation with—to indicate which percentage we were using in our notes and results, which was the ultimate goal. So we kept brainstorming.

Figure 1. Word clouds of brainstormed terms for both methods of measurement

2. ‘Factor’ vs. ‘Ratio’Another way to frame the distinction was one Justine sent over last March (you can see how long it’s been haunting us):

Justine: “I don't know why it is just recently that I have been re-thinking about it, but I might have something to add to the conversation about percentages in food. I don't know if it is still a issue in the lab, but anyways, I think you might be interested by my recent thoughts on it. I think it came because I had to explain my students about fermentation (always!). I suddenly remembered another scientific way to express a relative quantity. In science, when you have to do a 10% solution of something, you can either notate it with the % sign, or with the dilution factor 1:10. The factor means, for all scientists, that you have one part of something in a final volume of 10, so 1:10 is 1 part of something and 9 part of the other, always.I guess you have to be careful in the lab and not confuse it with a ratio (like we did for some fermentation recipes, ex: 1:5:9).Maybe you could add 'ratio' or 'factor' in front of each notation!”

Josh: “So if we were to write 1:10 for something, it's sort of like the 'scientific' or 'composition' measurement of 'factor' would read like '1 in 10 parts x', and the 'chef' or 'production' measurement of 'ratio' would read like '1 to 10 parts x'. Yet another way of illustrating the difference...”

Justine: “Factor is 1 of x and 9 of y for a total of 10xy; ratio is 1 of x and 10 of y for a total of 11xy. Maybe you can start a new way of writing and add some symbol to refer to what you are talking about, maybe an 'f' or a 'r' after the fraction, i.e. 1:10(f) for the former and 1:10(r) for the latter.”

3. ‘Production’ vs. ‘Composition’The possibilities branched rapidly and recursively. We ultimately settled on using mainly percentage notation instead of ratios, but both modes could be used depending on one’s preference (and Justine’s ‘Factor/Ratio’ notation could work well for the latter). Since I (Josh) have been mainly using percentages, I settled for a while on ‘Production’ and ‘Composition’ as my terms, which I notated with %P and %C and which correspond, respectively, to Arielle’s and my original proposal of ‘process’ and ‘product’.

4. ‘Pluscent’ vs. ‘Percent’I still wasn’t 100%C satisfied with this notation, because while it worked well enough (not brilliantly, but fine) in writing, it was clunky to say: “production percentage” is six syllables! It was only a few weeks ago, while finalising this draft, that the best solution so far emerged from the ether. Actually, it emerged from the keen mind of a friend named Dave Rowe, while he, his wife Pam and I were sharing a glass of wine and I was describing to them my on-going wrestling match with percentages. Dave’s observation was that perhaps we should look at the word ‘percent’ itself as a starting point from which to generate an entirely new term to distinguish between the two methods. He quickly did so by suggesting the neologism ‘pluscent’ (a percentage that ‘is added’ to 100) as the logical counterpoint to ‘percent’ (a percentage out of 100). My follow-up question to Dave was how he would notate a ‘pluscentage’, to which he suggested that we create a new symbol—we collectively arrived at the idea of combining ‘+’ with ‘%'. On platforms such as our website that do not allow such custom fonts in-text, I have settled for using '+%' in combination; otherwise, here is the glyph we designed (thanks to Rosemary, a former NFL intern and Artist-in-residence) and rendered as a font (thanks to Rosemary's friend Daniel, a graphic and web designer).

Visualising the gap

Table 1. Increasing gap between pluscentage and percentage for given weights.

Figure 2. Gap between percentage (plotted on the y axis) and pluscentage (plotted on the x axis). The curve gets shallower, which shows how percentage drops off more as pluscentage increases.

So, when it comes to making things, if one needs to reach a certain percent of an ingredient in the final mixture, one must bust out some algebra.Given the weight of the mixture to be added to, it is necessary to solve for x:

x = az

and

a = 100b/(100-b)

wherex is the amount to add;z is the amount to be added to;a is the pluscent of the addition; andb is the percent of the addition in the final mixture.

But fortunately, you don't have to do that, because we made a calculator. Actually, three. The ‘Pluscent calculator’ can be used to calculate pluscent, given the desired percent of the addition in the final mixture; the ‘Addition calculator’ can be used to calculate addition amount, given the weight of the mixture to be added to and the desired percent of the addition in the final mixture; and the 'Percent calculator' can be used to calculate the percent of an addition in a final mixture, given the pluscent (the opposite of the first).

For example: You are making a garum. Let’s say you have 2730g mackerel guts and 600g barley koji, and you want to figure out how much salt to add to reach, say, 12% in the final mixture. You would use the ‘Addition calculator’, put ‘3330’ (2730+600) in the first field, ‘12’ in the second field, and obtain a figure of 454g.If you wanted to figure out the pluscent for the salt, you would use the ‘Pluscent calculator’, insert ‘12’, and obtain 13.63.And let’s say you were working from a garum recipe for which you already had the salt pluscent, and wanted to know the salt percent in the final mixture. You would use the ‘Percent calculator’, insert ’13.63’, and obtain 12.

Further considerations

Of course, this calculator only works if you're dealing with 2 components—though one component can be composite, eg. the mixture of mackerel guts and koji in the example above. For multi-component ratios (salt : koji : legumes for a miso, for example) we’d have to make a more complex calculator, but it can be done.

The two measuring methods explored here are not the only ones out there. Baker’s percentages, for example, work differently—one ingredient, usually the most massive but also sometimes the most valuable, is set as a reference (100%), and the amount of every other ingredient is scaled as a percentage of the reference’s weight. Pluscentage can be thought of as the simplest baker’s percentage, where there are only two ‘ingredients’: the one to add and the one (or mixture of ingredients) to be added to. The advantage of baker’s percentages is that they can be used for more ingredients; the advantage of pluscentage might be that its relationship with percentage is more easily calculable, especially with recipes that change. For lots more on measuring methodology, check out Modernist Cuisine vol. 1.

Furthermore, of particular note for salt in fermentations is that it is not salt itself that matters, but how salt, and other compounds like sugar, hold onto water. What we are measuring here is water activity (Aw), and it is this measurement that in part determines whether or not certain microbes are able to grow. So really, the ideal situation would be to measure salinity in relation to water in a recipe (taking average moisture contents of constituent ingredients), but of course in practice this is somewhat difficult.

An experiment

While differences between these two (or more!) ways of measuring are clear in principle, and while I have started indicating which one I use in recipes, I still want to have some data that shows it matters when it comes to taste—and above what threshold. So I devised an experiment to address the role of this one variable in the complex phenomenon of fermentation.

Hypothesis:A certain fermentation model system will exhibit gastronomically significant differences above some threshold if only salt concentration is varied by percent and pluscent.

Materials:I made two different model fermentation systems—a low-salt miso and a high-salt miso—using Øland brown beans, pearled barley koji, filtered water, and sea salt (Table 2), in duplicate, each with three trials: one with salt by percent, one with salt by pluscent, and a negative control with no salt.

Methods: I took samples of ~5ml at 2-week intervals over the 3-month fermentation, for a total of 7 samplings, which are frozen and await metagenomic sequencing by Martin Abel-Kistrup and Tom Gilbert, part of the Gilbert Group at the Centre for GeoGenetics at the Natural History Museum of Denmark, University of Copenhagen. We have already collaborated with Martin and Tom on doing some metagenomic sequencing of the microbial ecologies of some of our vinegar barrels; this should be an interesting next experiment.I conducted a fast aroma and visual analysis after sampling for the seventh and final time and transferring the remainders of the final products to clean containers for cool storage.

Results:See Table 3 for some notes from the informal aroma and visual analysis I conducted.

Table 3. Fast sensory analysis notes from the different samples.

Conclusions:This is a very preliminary experiment, and it’s not yet done. It would be ideal to obtain more, and more rigourous, sensory analysis data (include tasting in addition to looking and smelling, gather sensory descriptors, serve samples blind, use ~10 panelists), and I'm dying to sequence the metagenomes of the samples to see if there are some differences in the microbial populations. Based on the preliminary results, I’d say it’s likely there are some differences happening in the microbial communities of the different samples.

Finally, I’m sure others have already thought about this measurement problem and come up with more elegant solutions for conceptualising, terming, and notating the different methods. It would be great to hear from you if you know of any existing materials.In the meantime I'm finding ‘pluscent’ and ‘percent’ pretty useful.

If you would like to use the pluscent symbol yourself, you can download the font here. The pluscent symbol is the only glyph in the font, and is inserted with the '%' key (shift+5 on English keyboards).

Anna and I taking our first samples.

Acknowledgements

We’d like to thank Justine, Guillemette, and other numbers-geekery-inclined team members past and present for contributing to this ongoing discussion; Dave Rowe and Pamela Camerra-Rowe for the stroke of brilliance that provided the world with ‘pluscent’ and the idea for its symbol; and Rosemary Liss and Daniel Givens for contributing their time and skills in creating the pluscent symbol in Illustrator and rendering it into a font with Fontello. Also many thanks to Anna Sigrithur for taking samples by herself multiple times while I was traveling in the fall.

At the end of the year in 2014, a month or so after moving into our new space, we had a Julefrokost to celebrate the year. I made a simple experiment with a few of my favourite items in the lab at the time: Jason's fermented giant puffball, quince balsamic/elder vinegar 'lees', and fireweed tea.

In some way it was quite old-school, banal even: a blade of raw endive with accoutrements. The endive provided fresh bitter snap for what made it, for me, other than an entirely predictable hors d'oeuvre.

In the winter of 2013, we were making a new batch of quince wine to top up our balsamic vinegar barrels just around the time we were also bottling the 'older elder' vinegar begun in the summer and fermented through the fall. We had a bit of extra quince wine, to which we added the extremely vigourous mother from the most successful batch of older elder vinegar. Left for six months in a warm cupboard on the boat, the mixture fermented and reduced into a thick, dark, exceptionally sour thing. We don't know quite what to call it (a not infrequent problem) but it is tasty. Informally I have been calling it 'quince vinegar lees'—not accurate but perhaps better than nothing. A little of it goes a long way.

At a first tasting it clearly needed some fat, and Roberto suggested using a nut oil, like walnut or hazelnut. I settled on a blend of both, incorporating the former's structure and the latter's aroma, and making a vinaigrette of sorts with the quince vinegar lees to brush into the endive before adding some wisps of fermented puffball.

It was still quite 'classic'. I thickened the vinaigrette and flipped the endive over.

I had powdered some of the fireweed tea as a final garnish, for a tannic, lightly lactic note up front.

This series is about oxidation, rancidity, and aging butter. Part 1 gave some background about butter, rancidity and the cultural context for eating aged butter. Part 2 explored the science of oxidation in fats and the safety of eating them. Part 3 was on culturing butters with unusual sources of bacteria. This part (finally!) is all about aging butter.

The primary aim of the project was to see if we could, by controlling the extent and pathways of aging, create butters with novel and desirable flavour profiles. Having settled on a flavoursome cultured butter, we started to carry out tests to control the conditions that lead to rancidification (as were laid out in part 2).

My hope at the start of the project was that, by letting the butter age and therefore develop mild rancid characteristics, the delicious butter cultured with our unique combination of LAB could be enhanced by some of the blue cheese and spicy notes characteristic of rancidity to give rise to an even more interesting, delicious butter: a product that, if we were to put our branding and marketing exec hats on, we might best call ‘Blue Butter’.

Figure 1. Butter samples using various, sometimes improvised, techniques to control the conditions they were exposed to.

So we exposed butter samples to a variety of different conditions for a period of up to 45 days: we vacuum-packed samples or left them exposed to oxygen in the air; we exposed samples to direct sunlight or kept them in the dark; we froze samples, refrigerated them, or kept them at room temperature. Would combinations of these processes produce notably different flavour profiles, and, more importantly, would any of these combinations offer promising gastronomic results?

Aged butters, cultured and uncultured

I ran simultaneous tests on cultured and uncultured butters, using the latter as a control for the former. The fresh uncultured butter was quite tasteless: thus, the effects on flavour of exposure to oxygen, light and different temperatures (as opposed to microbial activity) would, we hoped, be quite clearly discernible.

As expected, freezing the butters greatly slowed down any oxidation, hydrolysis or microbial activity and the flavours of these samples remained constant. Refrigeration did much the same. We corroborated these results with TBARS tests that showed only very tiny levels of oxidation products for chilled and frozen samples of both the cultured and uncultured butters (TBARS tests are a simple way to measure oxidation products, and they are discussed more fully in the addendum).

As the room-temperature butters were aged, a translucent ‘rind’ developed on their surface and various new aromas (eg. baby vomit—butyric acid!, blue cheese, Parmesan, linseed oil, petrol) and flavours (eg. blue cheese, Parmesan, linseed oil, spiciness, tanginess) developed. Furthermore, as the butters aged their texture became ‘smoother’ which was often pleasant.

Figure 2. Aged butters ready for taste testing

For the uncultured butters there were clear differences between the flavour profiles produced by exposing the butter to atmospheric oxygen but not light and vice versa. The former gave much less palatable petrol, linseed, and beef tallow flavours, while the latter gave much more enjoyable flavours redolent of aged hard cheeses and blue cheeses. The TBARS tests supported what we intuited: that the former’s oxidation was more advanced.

The most promising results were for samples stored for ~14–28 days in dark and full or partial vacuum, or those stored for ~7–14 days in daylight and full or partial vacuum. The smens I tasted on a visit to Morocco (after I had completed this project) were very close in taste to a number of these; in particular, aged hard cheese, blue cheese and baby vomit were descriptors that cropped up when I tasted a range of smens from 3 months to 2 years old.

Table 1. Tasting notes for uncultured butter after aging for 14 days at room temperature under the stated conditions.

For the cultured butters, unfortunately beyond ~10 days almost all the samples developed an unpleasant bitterness/sourness as a result of continued microbial activity and/or breakdown of compounds produced by the culturing. To distinguish between the two pathways, one could pasteurise cultured butter to kill any living microbes before aging. However, regrettably, I didn’t have time to perform these further tests during my three-month stay—or rather, I tried but I always ended up with clarified butter (ghee), which has very different textural properties to unclarified butter.

Smen

As mentioned in part 1, smen is an aged Moroccan butter, normally made by mixing butter with an infusion of thyme or oregano and then storing for several months to several years in, traditionally, clay pots.

Based on the encouraging results from the uncultured butter that had been kept in a full or partial vacuum and exposed to daylight, I made smens with a variety of Nordic ingredients in place of the herbs. Although their specific function in the making of smen is not documented, oregano and thyme are packed full of antioxidants [1], as are many Danish seaweeds [2]. therefore hoped that seaweeds would work similarly well .

After 30 days, the results of the following smen infusion trials were highly mixed:- Juniper bark—chalky, slightly soapy.- Birch bark—resinous, sweet like candy.- Toothed wrack seaweed—very pleasant, not a strong taste of seaweed; mild blue cheese, parmesan.- Grass kelp—creamier and more tangy than that toothed wrack seaweed smen, and a stronger note of seaweed.- I also made one with birch bark ash—the ash water was very alkaline—pH 13!—which caused the fat to start breaking down (saponification). The final smen had a pH of 10, which is straying towards dangerous territory so I only ate the smallest of dabs: predictably, it was soapy and unpleasant.

However, the best Nordic smen I made used bladderwrack (Fucus vesiculosus). After 15 days the bladderwrack smen tasted like a cross between a very mild blue cheese and a ranch dressing. After 30 days the blue cheese flavour had become much deeper and more rounded. I kept tasting it for up to 2 months (after which point I left the lab): throughout this period the flavour kept changing, but it remained good-tasting and, seemingly, safe. However, I suspect after 2 months in daylight it would be best to stabilise the butter by transferring it to the dark.

Seaweed smen

We served this at staff lunches melted through grains (rice, couscous or pearl barley) to which it added a complex buttery, blue cheese-like nuttiness.

1. Infuse 500 g of water with the bladderwrack by boiling vigorously for 5 minutes. Dissolve 2 tablespoons of salt and allow to cool to body temperature.2. In a container, pour the infusion over the butter and work them into each other. Leave overnight.3. Strain the water off, cover and store for 2 days at room temperature.4. Work the butter to remove any remaining water, pat the butter dry with kitchen towel and transfer to a sterilised glass jar.5. Store at room temperature in daylight (Danish early winter daylight!).

Tibetan butter tea is made with Yak butter that, as mentioned in part 1, is often described by Westerners as tasting rancid [3]. In Tibet and Nepal, they also use the butter tea to make tsampa, a dumpling made with roasted barley or wheat flour. Apparently the Dalai Lama eats it everyday for breakfast! Given the plenitude of funky butters I had at my disposal I was keen to try out both of these recipes.

Of the various teas hanging around in the lab, I found the most suitable was a Thai tea, Jing Shuan Oolong Tea, which, when 10 g is brewed in 450 g water for 3–4 minutes, tastes of peach and grapefruit, and has a good astringency. To make the butter tea, I mixed 50 g of tea with 5 g of butter. The aged butter that worked best was the uncultured butter that had been exposed to light but not oxygen for 1 month.

To make the tsampa, I then mixed enough butter tea with toasted rye flour to form small balls, ready to eat as they were.

The tsampa—nutty from the toasted rye, sweet and fragrant from the tea, and with a pleasing gnocchi-like texture—were quite enjoyable; I could imagine them, or some variant of them, becoming the latest go-to health craze (gluten-free, anti-oxidants from the tea etc. etc.).

In contrast, the butter tea by itself was just a bit weird. The mouthfeel was very creamy (much like bulletproof coffee), but because of its richness it was really more like a soup; for a European—perhaps especially a Briton—the name ‘tea’ jarred strikingly with my expectations of what it ‘should’ taste like.

However, pleasingly, I did find that butter tea made with aged butter was more flavoursome and palatable than that made with normal unaged butter. Gastronomically, the butter tea didn’t seem overly ripe for investigation (e.g. I can’t see it popping up on restaurant menus any time soon). Though I can easily imagine how in the challenging conditions of the Himalayas it is a very practical and soothing way of consuming energy in a very dense form.

Conclusions

Through working on this project and the process of writing these blog posts we realised that lipid rancidity is a complex topic that is, even from a chemical perspective, not wholly understood.

Although we didn’t produce any cultured aged butters that I was really happy with, the seaweed smens were great: their use as a flavour enhancer in e.g. stews, roasted meats and vegetables, grains, salads and dressings, could and should be pursued. It might be more difficult to control the aging process with already cultured butters, but with some additional trials and adjustments (e.g. pasteurisation of the cultured butter to inhibit further microbial activity, followed by aging) I am confident that a cultured aged butter with unique and delicious applications can be found.

When I started the project I was probably overly ambitious; I thought it was going to be quite easy to create some form of aged butter that I could eat with bread as an analogue of blue cheese. In hindsight that was naïve of me! After all, the great cheeses of the world have been perfected with knowledge developed over many hundreds of years. From the results of the work we did, it seems that, in whatever form it is made, an aged ‘Blue Butter’ is more likely to find use as an ingredient (e.g. used to make a beurre blanc or as per the suggested uses of the smen) rather than as a standalone product.

If anyone plays around with aging butter then please let us know; we’d love to hear about your findings.

Huge thanks to everyone at the lab who made my time there so special and particularly to Josh, Michael, Mogens Larsen Andersen (University of Copenhagen) and Kent Kirschenbaum (NYU/Experimental Cuisine Collective) for illuminating chats and guidance.

TBARS (2-Thiobarbituric acid reactive substances) tests are a relatively simple and inexpensive chemical test used to measure the extent of oxidation in a fat. They can be performed in a standard modern chemistry lab. TBARS, which include lipid hydroperoxides and aldehydes, are naturally present in systems in which lipid oxidation has taken place e.g. oxidised fats. It is generally accepted that as the level of oxidation increases so does the amount of TBARS present.

The TBARS tests gave basic quantitative support to what we intuitively expected and determined from our tasting of the butters. See Figure 9 for some representative data.

For both cultured and uncultured butters, the chilled samples exhibited somewhat more oxidation than the frozen samples, and the room temperature samples exhibited much more oxidised character than the chilled ones.

The cultured samples always exhibited more oxidised character than their uncultured counterparts, i.e. the presence of microbes increased oxidation (probably because of increased enzymatic oxidation).

Samples exposed to oxygen and light exhibited more oxidised character than counterparts that had been exposed to only light or only oxygen.

Samples exposed to only oxygen exhibited more oxidised character than counterparts exposed to only light. That is, oxidation from atmospheric oxidation was a greater problem than photo-oxidation caused by light. A practical kitchen use of this finding would be to stress the importance of storing butter and other oxidation-prone fats vac-packed, if possible.

For the uncultured butter, after 23 days, the samples exposed to both light and oxygen exhibited more oxidised character than their counterparts, but only by a little bit more. In contrast, after 43 days, they exhibited significantly more oxidised character than their counterparts. This seemed to reflect how oxidation reactions are free radical reactions which have a slow induction period followed by rapid propagation step (and at some point a termination step). Due to time constraints I was unable to complete the TBARS tests on the 43-day-old cultured butters.

Figure 9. TBARS results for aged butters. Control samples were vacuum-packed and kept frozen in the dark. The results are based on single measurements and error bars were not calculated. However, the potential error size can be gauged from the discrepancy between the 23- and 43-day-old control samples (the 23-day-old one should contain less than or the same amount of TBARS as the 43-day-old one).

The results from the TBARS tests show that they are a useful and valid way of evaluating the level of oxidation in butter samples like these, that there are quantitative differences between butters stored in different conditions, and that these difference may ultimately be qualified through a combination of sensory studies, chemical analysis, and consideration of proposed reaction mechanisms.